Operating system: windows 7 (at work - not my choice!)
Graphics card: GTX1080
Blender Version 2.79.6 fb057153b05
Edge slide clamp key not working.
Exact steps for others to reproduce the error
Create an object, enter edit mode, select a vertex/edge/face. Double tap G to edge slide, press C to slide 'beyond' the edge - nothing happens - the Clamp on/off text to the bottom left doesn't change - the yellow guide lines that should appear on the object do not appear.
**please note - I'd like to be using 2.80 now but I'm a Highways Civil Engineer doing visualisations and I really need the Offset add-on - I really hope it will be incorporated soon - it's my most used command by far!
Thanks for Blender!